Apparatus for producing low temperatures



Patented Apr. 14, 1925.

PATENT OFFICE.

PAUL HEYLANDT, OF SUDENDE, NEAR BERLIN, GERMANY.

APPARATUS FOR PRODUCING LOW TEMPERATURES.

Application filed January 3, 1921. Serial No. 434,832.

To all whom it may concern:

Be it known that I, PAUL HEYLANDT, a citizen of the Germany Republic,and a resident of Sudende, near Berlin, Germany, have invented certainnew and useful Apparatus for Producing Low Temperatures, of which thefollowing is a specification.

This invention relates in general to processes and apparatus forproducing low temperatures particularly for the liquefaction of gases.It relates more specifically to processes of this kind in which lowpressure gas compressors are employed. Some of the novel features of theprocess are the following.

During the circulation of the gas two heat exchanging processes takeplace, aseous air having a temperature of 15 elsius and compressed to apressure of 40 atmospheres is conducted through a heat exchanger inwhich it encounters two sources of cold.

The one source of cold consists of liquid air that is compressed to a.pressure of 200 atmospheres and imparts its cold to the said warm air orgas compressed by a compressor to 40 atmospheres. In thus yielding upits cold the liquid air becomes gaseous and its temperature is raised to15 Celsius. It is conducted in this warm state and at its high pressureof 200 atmospheres into an expansion machine in which it expands whilstperforming external work and cools down to from 180 to 192 Celsius. Thiscooled expanded air forms the second source of cold, to which theaforementioned air of a temperature of 15 Celsius compressed to 40atmospheres is subjected. The said cooled expanded air, after yieldingup its cold, is drawn in and recompressed by the compressor. Hence theair which issues fromthe gas compressor and, after circulating throughthe above described devices, returns to the gas compressor, is subjectedduring circulation to two heat exchanging processes which result fromthe path along which the air is conducted having the form of conduitsplaced one within the other or from the said path being so shaped as toturn back upon itself as it were a number of times. 1

In the known gas liquefying processes of Linde, Claude, and Mewes only afraction of the gas passed on by the compressor is liquefied. In Lindesrocess for instance only about 10 to 15% 0 this gas is liquefied,

whereas the present process enables as much as 100% of the gascompressed by the compressor to a pressure of 40 atmospheres to beliquefied.

To achieve this result with the processes employed hitherto it wasnecessary to use a gas compressor for 200 atmospheres.

In ,the present process the air compressed to 40 atmospheres isconverted into a liquid state by the two said sources of cold so thatonly a comparatively small liquid compressor is requlred for the purposeof raising the pressure of the liquid to 200 atmospheres. In this waythe advantage is gained that in place of a gas compressor of largeVolume a liquid compressor of small volume can be used, because thevolume ofv a given quantity of air is 800 times smaller in a liquidstate than in its gaseous state.

The present process will be described with reference to the accompanyingdrawing which represents diagrammatically la vertical section of acolumn comprising heat exchangers consisting of three tall annularchambers and a central cylindrical chamber.

The drawing also illustrates diagrammatical vertical sections of a highand low pressure compressor and of an expansion machine and the conduitsconnecting the compressors and the expansion machine to the column.

The column contains two tall annular chambers a and and a that are incommunication with each other through a connecting pipe la. Between thetwo annular chambers a and a is an intermediate annular chamber g, andthe inmost annular chamber a surrounds a central cylindrical chamber 7which is connected by aspiral conduit f and an exterior pipe to anexpansion machine 6 located in the coldest part of the apparatus andfrom which expanded gas is conducted into the middle annular chamber 9by means of branch pipes 9 7c is an air comressor that compresses airtaken in from t e outside atmosphere through the inlet a:

column when the process hasbeen properly Celsius.

pump p from the annular chambers a and a under a pressure of about 40atmospheres is forced against a pressure of 200 atmospheres into theheat exchanger 7. As the upper parts of the column are comparativelywarm the liquid air will commence evaporatin after rising a shortdistance in f and t e expansion due to the evaporation of the liquid aircauses a pressure of 200 atmospheres to be maintained in f and in thepipe leading out of it. Thus while a small volume of liquid gas istransferred by the pump p to the chamber f and thus raised from apressure of 40 atmospheres to 200 atmospheres a comparatively largevolume of gaseous air is kept at a pressure of 200 atinojs pheres by theevaporation taking place 1n a The temperature of the cold evaporated.air in f before reaching the top of the column willhave been raised toCelsius and this temperature will be increased still further in thehelical pipe 1 where it will reach Celsius. The pressure in f and in theconduit leading to the expansion machine '6, or to any other suitableform of expanding device such as a turbine, may be increased at will toa point that will suffice to cause its temperature to be lowered by itsexpansion in e-during which it also loses heat through performingexternal workto the boiling point of liquid air, viz. 180 to 182 Theexpanded cooled gas passes from the. expansion machine e through thebranched pipe g into the annular chamber 9 of the heat exchanger and inpassing through this chamber g the gas transfers its cold to theadjacent chambers a and a and receives warmth from the air in thesechamhere to such an extent that it passes out at the top of the columnat a temperature of 15 Celsius. Instead of passing into the atmospherethe air leaving-the column at the top may be drawn in by the compressork which as hereinbefore stated, also takes in fresh air or gas throughthe inlet 00. The

compressor 7:; raises the pressure of the said gases to a comparativelylow pressure that lies beneath the critical pressure (20 atmospheres inthe case of hydrogen) which in the case under consideration is 40atmospheres.

The gases or air after being purified and cooled by water are conductedthrough the pipe y into the top of the heat exchanger where they passdownwards in the annular chambers a, a and their temperature is loweredby the cold in g and f to about -.192 so that the air will liquefy.

The liquid pump p maintains a continuous circulation by pumping theliquid air from the bottom of a, a into thefchamber f i and therebyraises its pressure to 200 atmospheres.

The liquefied air 'or gas collecting in the annular chambers a, a may betappedofl' through a tap a.

Other advantages offered by this process in addition to those alreadymentioned are the following: The output of the apparatus account of thevolume of gas to be dealt with being much smaller, may also be muchsmaller and hence much cheaper and simpler than the cases of knownprocesses; for in order to produce 20 litres of liquefied gas per hourit will now not be necessary to compress 150 to 200 cubic metres of airper hour but onlyabout 16 obm the whole of which is now liquefied in anovel manner and thus yields 20 litres of liquid.

Another advantageous point is that no high compression pressure need beproduced by the gas compressor as it is only necessary to raise thepressure of the gas to be liquefied to the critical pressure which, inthe case of air, is 40 atmospheres.

- These two features operate to reduce the price of the apparatus tosuch an extent that it costs only 2/5 of the price of ordinary ap aratuswhilst giving the same output. nother advantage is obtained by ing thecold air through the helical pipe f at the topof the column instead ofconducting it straight from the middle chamber f to the expansionmachine 6. This advantage consists in the-fact that the air coming fromthe expansion machine e and passing up through the annular chamberbetween a and a and which air ordinarily leaves the apparatus at atemperature below 0 Celsius without accomplishing any useful end,effects a preliminary cooling of the gases passing through the helicalpipe f to the expansion machine. The cold producing effect of the plantis thus enhanced.

I claim A refrigerating apparatus comprising, in combination, a pair, ofconcentrically disposed annular members forming an inner chamber and anouter chamber in communication with each other near their lower ends,said chambers being spaced apart to provide an intermediate chambertherebetween and said inner'chambe'r enclosing a spaceforming acylindrical central chamber, an exansion machine disposed below saidchamers, a tubular coil in communication with said central chamber atthe upper end thereof and. with said expansion machine, a pipecommunicating with saidexpansion machine and with said intermediatechamber at the lower end thereof, a compressor in communication with theatmosphere and adapted to compress air to a PEGSSHIB of 40 atmospheres,a water cooler, a pipe in communication with said compressor and passingthrough said water cooler, said pipe comrequired for carrying out theprocess, on

sendmunicating with said outer and inner chambers at the upper endsthereof, and a sec- In testimony whereof I have signed this 0ndcompressor in communication with said specification in the presence oftwo witouter chamber and said central chamber at nesses.

their lower ends and. adapted to receive a i PAUL HEYLAND T i fluid fromthe outer cnamber and transfer Witnesses:

it to the central chamber under a pressure Kenn: Luzon;

of 200 atmospheres. Max JABIDUSKI. I

